Roles of DSCAM in axonal decussation and fasciculation of chick spinal interneurons
Roles of DSCAM in axonal decussation and fasciculation of chick spinal interneurons
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DOI：
10.1387/ijdb.160235ak
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发表时间：
2017-01-01
影响因子：
0.7
通讯作者：
Klar, Avihu
中科院分区：
文献类型：
--
作者：
Cohen, Oksana;Vald, Lilach;Klar, Avihu
胚胎神经管的腹中线，即底板，在胚胎发育过程中对轴突的引导具有深远的作用。底板衍生的引导信号吸引或排斥轴突，这取决于神经元亚型和发育阶段。Netrin-1及其受体在结肠癌（DCC）中缺失，是联合轴突向底板引导信号的关键成分。最近的研究表明，唐氏综合征细胞粘附分子（Dscam）是一种额外的Netrin-1受体。在这项研究中，我们研究了Dscam在指导确定的脊髓背间神经元种群中的作用。在鸡胚dI1、dI2和dI3中间神经元的背侧，通过分别增加或减少Dscam在这三个特定中间神经元群体中的表达，实现了Dscam的体内敲除和异位表达。神经元特异性Dscam功能的获得和丧失对d1 -3神经元轴突运动轨迹没有影响。共交神经元dI1c和dI2越过中线，同侧突起神经元dI1i和dI3同侧突起。然而，当Dscam表达减弱时，dI1轴突的束控减少。对底板的吸引或排斥都不需要磁力。相反，Dscam是轴突的束控所必需的，可能是通过嗜同性相互作用。
The ventral midline of the embryonic neural tube, the floor plate, has a profound role in guiding axons during embryonic development. Floor plate-derived guidance cues attract or repel axons, depending on the neuronal subtype and developmental stage. Netrin-1 and its receptor, Deleted in Colon Carcinoma (DCC), are the key constituents of commissurral axons guidance cues toward the floor plate. Recent studies have implicated Down Syndrome Cell Adhesion Molecule (Dscam) as an additional Netrin-1 receptor. In this study, we examined the role of Dscam in guiding defined spinal dorsal interneuron populations. In vivo knockdown and ectopic expression of Dscam were performed in the dorsal dI1, dI2 and dI3 interneurons of chick embryos, by separately increasing or decreasing Dscam expression in each of these three specific interneuronal populations. Neuron-specific gain and loss of function of Dscam had no effect on the axonal trajectories of dI1-3 neurons. The commissural neurons, dI1c and dI2, crossed the midline, and the ipsilaterally projecting neurons, dI1i and dI3, projected ipsilaterally. However, the fasciculation of dI1 axons was diminished when Dscam expression was attenuated. Dscam is not required for either attraction to or repulsion from the floor plate. In contrast, Dscam is required for the fasciculation of axons, probably via homophilic interaction.